1. Field of the Invention
This invention relates to flanged connections for process equipment and is particularly concerned with an improved system for retaining gaskets in the proper position during the makeup of such connections.
2. Description of the Prior Art
Flanged connections are used on process equipment of many different types, particularly large diameter vessels designed for operation at elevated temperature and pressure. Such connections normally require the use of a gasket between the machined faces of two flanged members to effect a seal. On heat exchangers and similar large diameter vessels, one of the flanged members generally contains an annular recess into which the gasket is placed. The flanged member adjacent that containing the recess normally includes a corresponding raised section or land which extends into the recess and contacts the gasket. A continuing problem with equipment of this type is that of keeping the gasket in the proper position while the connection is being made up, particularly where the faces of the flanged members and the gasket extend along vertical planes. The gasket normally tends to drop to the bottom of the recess and may fall out before the bolts can be tightened sufficiently to hold it in place. In many instances, the positioning of the flanged members must be done under conditions such that the gasket cannot be seen and the fact that it is not properly positioned is not discovered as the connection is being made up. This often results in leakage of the connection, necessitating that it be dismantled and made up again with a new gasket. If the improperly made up joint is not discovered during testing, it can lead to failure of the equipment and injury to personnel.
There have been many approaches to the problem of keeping gaskets in place during the makeup of flanged connections. One of the most common methods has been to apply grease to the gasket to hold it in place. This works reasonably well if enough grease is used but may result in leakage if the joint is heated during service and the grease melts. Adhesive tape has also been used to hold the gasket in place but this results in imbedding of the tape in the gasket when the connection is tightened and will again result in leakage when the tape disintegrates after the equipment has been put into service. Various types of retainers intended to extend through the bolt holes have been proposed but these are generally useful only with full face gaskets and cannot be used with flanged connections of the type referred to above. No wholly satisfactory method for properly positioning gaskets of this type has been available heretofore.